Turbine emergency shutdown
Thread Content
This post was last edited by yxmqh on 2010-11-11 at 11:27. In the event of an emergency shutdown caused by power outages or similar issues, it is necessary to minimize the coasting time in order to stop the turbine as quickly as possible; methods such as breaking the vacuum can be employed for this purpose. Why is that?
I understand it’s because there’s no lubricating oil; the supply time from the high-position fuel tank is limited
Lubricant supply issue. The process of breaking the vacuum can create resistance for the turbine, thereby enabling it to stop rotating rapidly.
Agree with the opinion above – to protect the bearings
Protects the bearings; oil is supplied from a high-level oil sump. Breaking the vacuum can reduce the idling time
If there is a power outage and no emergency power supply is available, the vacuum is disrupted, which shortens the coasting time; this ensures that the oil in the high-level tank continues to flow even when the unit stops, thus protecting the bearings
I’d like to ask gently, what are methods such as breaking the vacuum?
The turbine exhaust pipeline is equipped with a vacuum break valve; in some cases, it is replaced by an air valve of the start-up extractor, which is used to control the vacuum level during startup and to prevent a drop in vacuum level during shutdown.
During a power outage, the circulating water pumps and condensate pumps also stop operating; as a result, the condenser, steam seal heaters, and steam ejectors lose their cooling source. The condenser quickly develops positive pressure, and the vacuum break valve serves to relieve this pressure.
Reply to Floor 7: There is a atmospheric safety valve at the outlet of the condensing steam turbine; the vacuum level is maintained by a water seal, and damage to this water seal leads to a loss of vacuum.
Reply to 11# yxmqh: I think your answer is incorrect; how can a safety valve be used to break the vacuum? Steam ejector units generally use the air valve of the starting ejector as the vacuum break valve. The reason for not using a main exhaust valve is probably to account for the effect of temperature on the exhaust pump. For other exhaust systems, check valves are installed on the air pipelines; a separate vacuum break valve is provided, and the outlet is indeed sealed with condensed water.